Diazonium compounds and diazotype materials containing them



United States Patent 3,442,650 DIAZONIUM COMPOUNDS AND DIAZOTYPE MATERIALS CONTAINING THEM Andreas Joseph Johannes Hendrickx and Bernardus Hubertus Huibers, Veulo, Netherlands, assiguors to Chemische Fabriek L. Van Der Grinten N.V., Veulo, Netherlands, a Dutch corporation No Drawing. Filed Mar. 10, 1966, Ser. No. 533,257 Claims priority, application Netherlands, Mar. 12, 1965, 6503184 Int. Cl. G03c 1/54; C07c 113/00 US. CI. 96-91 10 Claims ABSTRACT OF THE DISCLOSURE Highly light-sensitive fast-developing diazotype materials which give strong images with little or no background offshades or staining are obtained by providing and utilizing in the light-sensitive layers new para-(tertiary) amino- 2-halo-3-(non-substituted or alkylor halo-) phenoxy benzene diazonium compounds in which one of the tertiary amino substituents is alkyl, branched alkyl or aralkyl, and the other is alkyl, branched alkyl, cycloalkyl or aralkyl. Particularly suitable for one-component diazotype layers are 4-dialkylamino-3-(chloroor bromo-) phenoxy-Z-chlm robenzene diazonium compounds in which the alkyl groups contain at most four C atoms; materials made with these develop rapidly with weakly acid bufiered phloroglucinol solutions, yielding black images on bright white or foggy gray backgrounds.

This invention relates to diazonium compounds of a new type and to diazotype material manufactured with the aid of these diazonium compounds. The diazotype material may be so-called one-component diazotype material which is developed with a liquid containing an azo-coupling component, so-called two-component diazotype material which is developed with the aid of ammonia vapour, or heat-developable diazotype material.

Besides adequate light-sensitivity, suitable coupling activity, and reasonable stability, diazonium compounds for sensitizing diazotype material should, as a rule, have a number of other properties. A very important one of these is that the photo-decomposition should form products which are completely or almost completely colourless, which when exposed to light show little or no staining and which do not actively react with diazonium compounds to yield dyestuffs.

If the photo-decomposition product is stained, copies made on the diazotype material also show a stained, completely exposed background. This is especially disadvantageous when the support of the diazotype material is white paper or when the support is transparent and the copy is to serve as an intermediate for further copying on diazotype material. Another disadvantage arising when the photo-decomposition product tends to stain when exposed to light, is the yellowing which the copies will show with age.

In recent years diazonium compounds of very high light-sensitivity have come into use for sensitizing diazotype materials. These compounds are chiefly benzene diazonium compounds having a tertiary amino group in the para-position with respect to the diazonium group and an etherified hydroxyl group in the meta-position, and possibly a further substituent, such as alkoxy, alkyl or halogen, in the para-position with respect to the etherified hydroxyl group. (Compare British patent specifications Nos. 867,629, 867,630, and 888,598.)

3 ,442,650 Patented May 6, 1969 British patent specification No. 919,037 describes diazonium compounds of the general Formula I in which X is an anion, Y is, for example, a hydrogen atom or a halogen atom or a methyl, alkoxy, or phenoxy group, R represents a substituted or non-substituted phenyl group, and R and R represent an alkyl, cycloalkyl or aralkyl substituent, which may or may not be further substituted. R and R together with the nitrogen atom may also form a heterocyclic ring.

These diazonium compounds are also very light-sensitive; however, they have a higher coupling activity than the corresponding compounds with an alkoxy group in meta-position with respect to the diazonium group, and consequently are better suitable for application in onecomponent diazotype material which is developed with weakly acid buffered phloroglucinol developers.

However, as compared with the diazonium compounds, such as 4-diazo-2,5-dialkoxy-N-benzoylaniline, 4-diazo- 2,5-dialkoxydiphenyl, and 4-diazo-2,5-dialkoxyphenyl-ptolylthioether, which were previously used on a large scale in one-component diazotype material to be developed with weakly acid phloroglucinol developers, their coupling activity is on the low side, so that diazotype materials sensitized with them have the drawback of a relatively low developing speed, which manifests itself in that it takes a relatively long period of time before the image becomes sufliciently visible. One-component diazotype material sensitized with a diazonium compound according to general Formula I yields copies which present a somewhat stained completely exposed background and show a not-negligible yellowing when exposed for a considerable time to daylight or to the light of high-pressure mercury vapour lamps.

The invention relates to diazonium compounds of a new type and to diazotype material manufactured with the aid of these compounds, which material avoids or minimizes the disadvantages described above with respect to the known materials.

According to the present invention there are provided diazonium compounds of general Formula II in which X is an anion and Y is a halogen atom, R represents a substituted or non-substituted aryl group, R represents a substituted or non-substituted alkyl, branched alkyl or aralkyl group, and R represents a substituted or nonsubstituted alkyl, branched alkyl, cycloalkyl or aralkyl group.

The diazonium compounds according to the invention are very light-sensitive and yield both light-coloured and dark azo-dyestutfs with the azo-coupling components commonly used in the diazotype process. They couple more actively, bleach out more clearly, and form less reactive photo-decomposition products than the diazonium compounds according to general Formula I.

Diazotype materials sensitized with diazonium compounds according to the invention have a higher developing speed and yield copies which have a clearer completely exposed background and show less yellowing than corresponding diazotype material sensitized with a diazonium compound according to general Formula I.

The diazotype material according to the invention is preferably one-component diazotype material.

The following table provides a list, though not a complete one, of diazonium compounds which can be used with good results in diazotype material according to the invention:'

Table 4-diazo-3-fluoro-2- 4'-methylphenoxy N,N-diethylaniline 4-diazo-3-bromo-2-phenoxy-N,N-dimethylaniline 4-diazo-3-chloro-2- (4-chlorophenoxy -N,N-dimethylaniline 4-diazo-3-chloro-2- (4-chlorophenoxy -N,N-diisobutylaniline 4-diazo-3-chloro-2-( 4'-chlorophenoxy) -N,N-di (2'-acetoxyethyl) aniline 4-diazo-3-chloro-2-( 2,4-dibromophenoxy) -N,N-diethylaniline 4-diazo-3-iodo-2- 4'-methylphenoxy -N,N-dimethylaniline 4-diazo-3-chloro-2- (4'-chlorophenoxy) -N,N-di- (2'-chloroethyl aniline 4-diazo-3-chloro-2- (4'-chlorophenoxy) -N-methyl-N- cyclohexylaniline 4-diazo-3-chlor0-2- (4'-chlorophenoxy) -N-methyl-N- benzylaniline 4-diazo-3-chloro-2- (2'-chlorophenoxy) -N-(2'-hydroxyethyl -N-benzylaniline 4-diazo-3-chloro-2- (4-chlorophenoxy -N-benzyl-N-cyclohexylaniline 4-diazo-3-chloro-2- (4'-chlorophenoxy -N,N-dibenzylaniline.

These compounds can be used as diazonium salts, e.g. as diazonium chloride, sulfate, or metal chloride double salt, such as chlorozincate, chloromanganate and chlorostannate, as diazonium borofiuoride or diazonium aryl sulfonate.

They can be applied in diazotype material individually, mixed together, or in admixture with diazonium compounds of other types. It goes without saying that a diazotype material according to the invention, accordingly as it contains a higher content of another diazonium compound, will present the specific advantages of the diazonium compounds according to the invention to a less degree.

With the diazonium compounds according to the invention the familiar supports, such as paper, tracing paper, printing-plate paper, tracing linen, opaque linen, synthetic paper, metal sheets, glass fibre, polyester film and the like can be sensitized. The diazonium compound may or may not be incorporated in a hydrophilic or hydrophobic film layer.

Preferred diazonium compounds according to the invention are those carrying a chlorine or a bromine atom in the ortho-position with respect to the diazonium group, a phenoxy group substituted with one or more halogen atoms in the meta-position, and in the para-position a dialkylamino group the substituted or non-substituted alkyl groups of which each carry at most 4 C-atoms.

When developed with weakly acid buffered phloroglucinol developers, diazotype material sensitized with these diazonium compounds furnishes copies in azo-dyestutfs which in the diazotype process are called neutral black. The developing speed of such diazotype material is higher than that of diazotype materials sensitized with the corresponding diazonium compounds of general Formula I. The completely exposed background of the copies is bright white; and shows-only little yellowing when exposed to daylight or to the light of a high-pressure mercury vapour lamp; the so-called foggy background of the copies is a fine neutral grey.

In the diazotype material according to the invention the conventional auxiliary agents can be used, e.g. acids, such as citric acid, tartaric acid and boric acid; stabilizers, such as benzene and naphthalene sulfonic acids, p-phenolsulfonic acid, and their water-soluble salts; metal salts, such as zinc chloride, magnesium chloride, nickel sulfate and alum; materials which serve to improve the developing speed, such as glycerol, polyethylene glycol, urea, thiosinamine and the like; surface-improving substances, such as finely divided silicon dioxide (colloidal or non-colloidal), aluminum oxide, barium sulfate and rice starch; binders, such as gelatin, gum arabic, cellulose ethers, starch derivatives, polyvinyl alcohol; dispersions of synthetic resins, such as dispersions of cationic, non-ionic, and anionic polyvinyl acetate; substances which serve to stabilize the background of the copies, such as thiourea.

The phloroglucinol developers which are used in the one-component diazotype process often vary as to their composition and acidity. Below, two weakly acid phloroglucinol developers are described which are employed in practice and are used for development in a number of the following examples.

Developer A is a solution of:

Phloroglucinol g 4 Acetoacetanilide g 0.1 2-ethylhexyl sulfate ml 3 Beet sugar g 15 Benzoic acid g 2.5 Sodium benzoate g 14 Sodium formate g-- 135 in 1000 ml. of water.

The pH of this liquid is approximately 5.8.

Developer B is a solution of:

Phloroglucinol 6.5 Resorcinol 4 Thiourea 10 Sodium dibutylnaphthalene sulfonate 2 Sodium formate 14 Sodium benzoate 22 Trisodium citrate (2 aq.) 49 Citric acid 1.2

in 100 ml. of water.

The pH of this liquid is approximately 6.5.

The following examples will serve to illustrate the invention:

EXAMPLE I (A) A sheet of white base paper for the diazotype process, of weight g./m. is sensitized with a liquid containing:

4-dimethylamino-3-(4'-chlorophenoxy)-2-chlorobenzene diazonium chloride, zinc chloride double (-B) Another sheet of white base paper for the diazotype process, of weight 80 g./m. is sensitized with a liquid containing:

4-dimethylamino-3-(4-chlorophenoxy)-2-clrlorobenzene diazonium chloride, zinc chloride double salt 25 Citric acid g S Saponin g 0.2 Water ml 1000 and dried.

Both diazoty-pe papers are very light-sensitive. Diazotype paper A develops somewhat more rapidly than diazotype paper B.

A strip of each sheet is imagewise exposed underneath a transparent ink drawing until the diazonium compound underneath the image-free portions of the drawing has completely bleached out, and then both are developed with developer B. The copies thus obtained show a black image on a white background. The background of copy A is whiter than that of copy B, and moreover it shows less yellowing when the copies are exposed to daylight or to the light of a high-pressure mercury vapour lamp.

The diazonium compound according to the invention used in this example was prepared as follows:

With 4-chlorophenol and potassium hydroxide, 2,3-dichloronitrobenzene was converted into 3-chloro-2-(4- chlorophenoxy)-nitrobenzene. Its nitro group was reduced to an amino group. The amino group was tosylated. The product thus obtained was nitrated to 4-nitro-3-chloro-2 (4'-chlorophenoxy)-N-tosylaniline, which was methylated, saponified, and methylated again. From the 4-dimethylamino-3-(4-chlorophenoxy)-2-chloro-nitrobenzene thus prepared the diazonium chlorozincate was obtained in the usual way by reduction and diazotization.

EXAMPLE II White base paper for the diazotype process, of weight 80 g./m. is sensitized with a solution containing 4-di('-acetoxyethyl amino-3-(4'-chlorophenoxy)-2- chlorobenzene diazonium chloride, zinc chloride in 1000 ml. of water and dried.

A sheet of the diazotype paper thus obtained is imagewise exposed underneath a transparent ink drawing until the diazonium compound underneath the image-free portions of the drawing has completely bleached out, and is then developed with developer A.

The copy shows a violet-black image on a bright white background.

If the above-mentioned sensitizing liquid contains an equivalent quantity of the corresponding compound with a -chloro-substituent, the diazotype paper thus obtained develops somewhat more slowly, bleaches out with a somewhat more pronounced stain, and gives copies which show stronger yellowing when exposed to daylight.

The diazonium compound used in this example was prepared as follows:

The nitro group of 3-chloro-2-(4-chlorophenoxy) nitrobenzene was reduced to an amino group, which was converted with epoxyethane into a di-(2-hydroxyethyl) amino group, from which a di(2'-acetoxyethyl)amino group was obtained with the aid of acetic anhydride. The product thus prepared was nitrated. From the 4-nitro-3- chloro 2 (4'-chlorophenoxy)-N,N-di(2-acetoxyethyl) aniline thus formed, the diazonium salt was prepared in the usual way by reduction and diazotization.

EXAMPLE III An offset-printing plate of paper is sensitized with a liquid containing:

4-N-methyl-N-benzylamino-3-(4'-chlorophenoxy)-2- chlorobenzene diazonium chloride, zinc chloride The light-sensitive planographic printing plate thus obtained is exposed underneath a negative original until the 6 diazonium compound underneath the image-free portions of the original has completely bleached out, and is then developed by rubbing the light-sensitive side of the plate with a solution containing:

5 200 g. of sodium 2-acetoacetaminonaphthalene-6,8-disulfonate in 1000 ml. of water.

After the development, the plate is sponged off with water. It shows a white image on a yellow background. The plate is placed in an olfset printer. At least 100 good positive offsetprints can be made from it.

The diazonium compound used in this example was prepared as follows:

3-chloro-2-(4'-chlorophenoxy)aniline was tosylated, nitrated, and methylated. After saponification of the tosylamino group the 4 nitro-3-chloro-2-(4'-chlorophenoxy)- N-methylaniline obtained was benzylated. From the 4- nitro-3-chloro 2 (4' chlorophenoxy) N methyl N- benzylaniline, the diazonium salt was obtained in the usual way by reduction and diazotization.

The present invention is not to be considered restricted to particulars of any of the compounds, materials or examples hereinabove described except as may be required by a fair construction of the appended claims, for various modifications and substitutions of equivalent nature will become available to those skilled in the art upon consideration of the nature of this invention.

What is claimed is:

1. A diazonium compound of the general formula,

IIIQX wherein:

X is an anion,

Y is a halogen atom,

R is a non-substituted or lower alkylor halogensubstituted phenyl group,

R is a lower alkyl, lower branched alkyl or benzyl group, and

R is a lower alkyl, lower branched alkyl, cyclohexyl or benzyl group.

2. A diazonium compound according to claim 1, wherein:

R is a halogen-substituted phenyl group and each of R and R is an alkyl group having at most 4 C atoms.

3. A diazonium compound according to claim 1, namely, a 4 dialkylamino 3 chlorophenoxy-Z-chlorobenzene diazonium compound.

4. A diazonium compound according to claim 1, namely, a 4 N alkyl-N-benzylamino 3 chlorophenoxy- 2-chlorobenzene diazonium compound.

5. A diazonium compound according to claim 1, namely, a 4 N benzyl-N-cyclohexylamino 3 cyclophenoxy- 2-chl0robenzene diazonium compound.

6. A diazonium compound according to claim 1, namely, a 4 dibenzylamino 3 chlorophenoxy-Z-chlorobenzene diazonium compound.

7. A diazonium compound according to claim 1, namely, a 4 dimethylamino 3 chlorophenoxy-Z-chlorobenzene diazonium compound.

8. A diazonium compound according to claim 1, namely, a 4 N methyl-N-benzylamino-3-chlorophenoxy- 2-chlorobenzene diazonium compound.

9. A diazotype material comprising a support carrying a light-sensitive layer containing a diazonium compound as defined in claim 1.

10. A one-component diazotype material comprising a support carrying a light-sensitive layer containing, in the 7 8 substantial absence of an azo coupling component, a NORMAN G. TORCHIN, Primary Examiner. diazonium compound as defined in claim 2. Q BOWERS Assistant Examiner References Cited Us CL X FOREIGN PATENTS 5 260-141, 142; 96-49, 75, 33

919,037 2/1963 Great Britain. 6,407,303 1/1965 Netherlands. 

